<?php
	//http://www.linuxjournal.com/article/9585?page=0,3
	function isValidEmail($email)
	{
		$isValid = true;
		$atIndex = strrpos($email, "@");
		if (is_bool($atIndex) && !$atIndex)
		{
			$isValid = false;
		}
		else
		{
			$domain = substr($email, $atIndex+1);
			$local = substr($email, 0, $atIndex);
			$localLen = strlen($local);
			$domainLen = strlen($domain);
			if ($localLen < 1 || $localLen > 64)
			{
				// local part length exceeded
				$isValid = false;
			}
			else if ($domainLen < 1 || $domainLen > 255)
			{
				// domain part length exceeded
				$isValid = false;
			}
			else if ($local[0] == '.' || $local[$localLen-1] == '.')
			{
				// local part starts or ends with '.'
				$isValid = false;
			}
			else if (preg_match('/\\.\\./', $local))
			{
				// local part has two consecutive dots
				$isValid = false;
			}
			else if (!preg_match('/^[A-Za-z0-9\\-\\.]+$/', $domain))
			{
				// character not valid in domain part
				$isValid = false;
			}
			else if (preg_match('/\\.\\./', $domain))
			{
				// domain part has two consecutive dots
				$isValid = false;
			}
			else if (!preg_match('/^(\\\\.|[A-Za-z0-9!#%&`_=\\/$\'*+?^{}|~.-])+$/', str_replace("\\\\","",$local)))
			{
				// character not valid in local part unless 
				// local part is quoted
				if (!preg_match('/^"(\\\\"|[^"])+"$/', str_replace("\\\\","",$local)))
				{
					$isValid = false;
				}
			}
			else if (!preg_match('/.+\..+/', $domain)) //if domain does not have a period; added by JD Reddaway
			{
				$isValid = false;
			}
			
			/* Does not work on usbwebserver
			if ($isValid && !(checkdnsrr($domain,"MX") || checkdnsrr($domain,"A")))
			{
				// domain not found in DNS
				$isValid = false;
			}
			*/
		}
	 return $isValid;
	}
	
	function usernameIsValidLength($username)
	{
		return strlen($username) <= 30;
	}
	
	function passwordIsValidLength($password)
	{
		return strlen($password) <= 50;
	}
?>